Primary Structure of the Porcine 89-kDa Enamelin

Fukae, Makoto; Tanabe, T.; Murakami, Chikage; Dohi, Naofumi; Uchida, Takashi; Shimizu, Masaharu

doi:10.1177/08959374960100020201

Cited by 106 publications

(104 citation statements)

References 14 publications

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“…Pig enamelin is secreted as a 186-kDa (1104 amino acids) glycoprotein that is rapidly processed, probably by MMP-20, in the extracellular space (21). The secreted protein is processed from its C terminus to generate 155-, 145-, and 89-kDa (Met 1 -Trp 627 ) N-terminal cleavage products, but these cleavage products do not last long and are found only near the enamel surface (41,62). Secretion, proteolytic processing, and reabsorption of selected cleavage products back into ameloblasts determine the makeup of the organic matrix that controls mineralization.…”

Section: Discussionmentioning

confidence: 99%

“…These enamel proteins have multiple glycosylation sites and other post-translational modifications, even hydroxyproline (41,42), and efforts to generate recombinant forms with the appropriate modifications have failed to produce them in any significant quantity (43). Therefore, it is currently impossible to reconstitute the secretory stage extracellular matrix and recapitulate the formation of enamel crystals in vitro.…”

Section: Correct Targeting Of the Transgene Was Confirmed By Southementioning

confidence: 99%

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Enamel Defects and Ameloblast-specific Expression in Enam Knock-out/lacZ Knock-in Mice

Smith

et al. 2008

Journal of Biological Chemistry

151

193

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Enamelin is critical for proper dental enamel formation, and defects in the human enamelin gene cause autosomal dominant amelogenesis imperfecta. We used gene targeting to generate a knock-in mouse carrying a null allele of enamelin (Enam) that has a lacZ reporter gene replacing the Enam translation initiation site and gene sequences through exon 7. Correct targeting of the transgene was confirmed by Southern blotting and PCR analyses. No enamelin protein could be detected by Western blotting in the Enam-null mice. Histochemical 5-bromo-4-chloro-3-indolyl-␤-D-galactopyranoside (X-gal) staining demonstrated ameloblast-specific expression of enamelin. The enamel of the Enam ؉/؊ mice was nearly normal in the maxillary incisors, but the mandibular incisors were discolored and tended to wear rapidly where they contacted the maxillary incisors. The Enam ؊/؊ mice showed no true enamel. Radiography, microcomputed tomography, and light and scanning electron microscopy were used to document changes in the enamel of Enam ؊/؊ mice but did not discern any perturbations of bone, dentin, or any other tissue besides the enamel layer. Although a thick layer of enamel proteins covered normal-appearing dentin of unerupted teeth, von Kossa staining revealed almost a complete absence of mineral formation in this protein layer. However, a thin, highly irregular, mineralized crust covered the dentin on erupted teeth, apparently arising from the formation and fusion of small mineralization foci (calcospherites) in the deeper part of the accumulated enamel protein layer. These results demonstrate ameloblast-specific expression of enamelin and reveal that enamelin is essential for proper enamel matrix organization and mineralization.

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Section: Discussionmentioning

confidence: 99%

Section: Correct Targeting Of the Transgene Was Confirmed By Southementioning

confidence: 99%

Enamel Defects and Ameloblast-specific Expression in Enam Knock-out/lacZ Knock-in Mice

Smith

et al. 2008

Journal of Biological Chemistry

151

193

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“…The SDS-PAGE electrophoretic profile of whole enamel homogenates from immature enamel is very complex and represents a composite image of both newly secreted and partially degraded forms from both categories of proteins (reviewed in Smith and Nanci 1996). Enamelin, ameloblastin (also known as sheathlin and amelin), and tuftelin are the best-known members of the nonamelogenin family (Deutsch et al 1991(Deutsch et al ,1995bCerny et al 1996;Fukae et al 1996;Krebsbach et al 1996;Hu et al 1997a,b). A glycosylated and sulfated nonamelogenin with molecular weight near 65 kD and major fragmented forms near 50 and 25 kD has also been described in rat enamel Smith and Nanci 1996).…”

mentioning

confidence: 99%

Comparative Immunochemical Analyses of the Developmental Expression and Distribution of Ameloblastin and Amelogenin in Rat Incisors

Nanci

Zalzal

Lavoie

et al. 1998

J Histochem Cytochem.

128

155

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SUMMARYMineralized tissues are unique in using proteins to attract and organize calcium and phosphate ions into a structured mineral phase. A precise knowledge of the expression and extracellular distribution of matrix proteins is therefore very important in understanding their function. The purpose of this investigation was to obtain comparative information on the expression, intracellular and extracellular distribution, and dynamics of proteins representative of the two main classes of enamel matrix proteins. Amelogenins were visualized using an antibody and an mRNA probe prepared against the major alternatively spliced isoform in rodents, and nonamelogenins by antibodies and mRNA probes specific to one enamel protein referred to by three names: ameloblastin, amelin, and sheathlin. Qualitative and quantitative immunocytochemistry, in combination with immunoblotting and in situ hybridization, indicated a correlation between mRNA signal and sites of protein secretion for amelogenin, but not for ameloblastin, during the early presecretory and midto late maturation stages, during which mRNA signals were detected but no proteins appeared to be secreted. Extracellular amelogenin immunoreactivity was generally weak near secretory surfaces, increasing over a distance of about 1.25 m to reach a level slightly above an amount expected if the protein were being deposited evenly across the enamel layer. Immunolabeling for ameloblastin showed an inverse pattern, with relatively more gold particles near secretory surfaces and much fewer deeper into the enamel layer. Administration of brefeldin A and cycloheximide to stop protein secretion revealed that the immunoblotting pattern of amelogenin was relatively stable, whereas ameloblastin broke down rapidly into lower molecular weight fragments. The distance from the cell surface at which immunolabeling for amelogenin stabilized generally corresponded to the point at which that for ameloblastin started to show a net reduction. These data suggest a correlation between the distribution of amelogenin and ameloblastin and that intact ameloblastin has a transient role in promoting/stabilizing crystal elongation. A meloblasts , like all hard tissue-forming cells, release an intricate set of extracellular matrix proteins optimized for promoting the development of a closely associated mineral phase (reviewed in Deutsch et al.

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“…For this, one should consider that these cells have a different origin; epithelial to ameloblasts and cells derived from the neural crest to the odontoblasts and that each cell type produces different matrices, respectively enamel and dentin. In studies, using scanning electron microscopy and in situ hybridization was observed that enamelysin is secreted by ameloblasts and odontoblasts within enamel and dentin matrices (Bourd-Boittin et al; Furkae et al, 1996).…”

Section: Discussionmentioning

confidence: 99%

Expression of Mmp-20 in Dental Germs of Human Fetus

et al. 2014

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SUMMARY:During experiments in animal studies, it has been observed that enamelysin is expressed during tooth development in the late secretory stage of amelogenesis but not in the mature enamel. The aim of this research was to determine the location of MMP-20 in human tooth germs in the different structures of the enamel organ. The detection of MMP-20 was performed by immunohistochemistry in 20 specimens obtained from human fetuses. Immunostaining of MMP-20 was observed from the presecretor stadium in stellate reticulum and intermediate stratum and in the basal portion of ameloblasts in the secretory stage in stellate reticulum, stratum intermedium, secretory ameloblasts, odontoblasts and dental papilla. The results of this research show the location of MMP-20 in tooth germ development in humans and provides the foundation for future research about the process of dental organ formation.

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Primary Structure of the Porcine 89-kDa Enamelin

Cited by 106 publications

References 14 publications

Enamel Defects and Ameloblast-specific Expression in Enam Knock-out/lacZ Knock-in Mice

Enamel Defects and Ameloblast-specific Expression in Enam Knock-out/lacZ Knock-in Mice

Comparative Immunochemical Analyses of the Developmental Expression and Distribution of Ameloblastin and Amelogenin in Rat Incisors

Expression of Mmp-20 in Dental Germs of Human Fetus

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